The Mustang, designed initially to meet a British requirement for fighter
service in Europe, became the leading US fighter in the European Theater of
Operation during the final months of the war. The Mustang was designed and
rolled out in 117 days. It was first flown on October 26, 1940. The P-51is the
synergism of every contemporary advanced aerodynamic and structural design;
primarily, it was the first fighter with a laminar wing design. As a result,
it held an exceptional internal fuel capacity and low drag enabling it to fly an
extended combat radius.

The RAF first flew the P-51 on July 27, 1942 as the MK I Mustang, of which 620
were ordered. Although the aircraft had great potential, it was limited by its
Allison engine and relegated primarily to ground attack and reconnaissance
roles.

The USAAF ordered 500
Mustangs, the first buy as A-36A dive-bombers in late 1942. With an Allison
powered V-1710-87 engine, the aircraft demonstrated high power at low level;
however, it was inefficient above 15,000 feet with it's single-stage
supercharger. The aircraft wasn't really wanted for an attack role, but was
employed as a means to maintain the production line while the merits of the
airframe was being argued. The A-36A was named the "Apache", then later the
"Invader" until the name "Mustang" stuck. The aircrafts were moderately
successful in the Mediterranean area of operation; claiming its share of aerial
victories against the Luftwaffe in air-to-air combat.

Cautiously, the USAAF
ordered an initial 150 P-51s mounted with four 20 mm cannons. Thereafter, 310
P-51As were ordered, with a 1,200 hp V-1710-81 engine, and four 0.5-in machine
guns with racks for two 500-lb bombs.

The British took a dramatic
step that began to turn off the cautious attitude toward the Mustang by
proposing the Merlin engine be fitted into the air frame. There was even
discussion that the engine should be placed behind the cockpit, similar to the
P-39 configuration. In 1942, with installation of the two-stage Merlin engines
and four-bladed propellers, the Mustang performed extremely well, exceeding 400
mph; and, the transformation produced a fighter that could equal or outperform
any other aircraft in the air at that time. North American developed plans to
manufacture the P-51 with the license-built Merlin 61, the Packard V-1650-3
in-line engine.

The USAAF ordered 2,200
P-51Bs followed on by the P-51Cs. The aircrafts were mounted with six 0.5
machine guns. The P-51D variant was ordered in 1943 and was introduced with the
bubble canopy and dorsal fin to control stability problems. Even though the
Malcom hood, which enhanced visibility on the British Mustang Mk II and Mk III,
was employed by the USAAF, it was the bubble canopy that became the standard
feature of the P-51. Few P-51Ds were operated by the British as the Mustang Mk
V. Later P-51Ds included an additional 85-gal fuel cell behind the pilot's
seat. This enabled the Mustang's combat radius to extend from England to Berlin
and back.

In an effort to lower the
Mustang's weight, the P-51H variant came about with a taller tail, of which 555
were manufactured. This version came late into the war and flew missions from
the Philippines prior to VJ day.

The P-51K was the Dallas,
Texas variant of the Inglewood, California
P-51D, sporting a different propeller, of which 1,500 were built.

In combat, the Mustang
proved to be significant in its role to wartime victory. The aircraft was
employed throughout 40 USAAF fighter groups and 31 RAF squadrons. The P-51
Mustang's combat record is generally considered to consist of: 4,950 aerial
victories, and 4,131 ground kills resulting in an 11:1 "kill ratio".